Leibniz-Institut für Lebensmittel-Systembiologie
an der Technischen Universität München

Programmbereich IWorking Group I

Working Group I. Structure and Bioactivity of Low-Molecular Food Ingredients (Hedonic Value)

Head: Priv.-Doz. Dr. Martin Steinhaus (until September 2016: Prof. Dr. Peter Schieberle)

Research:

Current projects of the working group are focused on the characterisation of naturally present odour-active compounds in foods and beverages and their changes on the way from the raw material to the consumer.

Compounds detected with the sense of smell are among the most important quality parameters in foods and beverages. They are absolutely crucial for the hedonic value of anything we consume as they predominantly account for the culinary joy during eating and drinking. It is actually the sense of smell located in our nose (and not the sense of taste located on the tongue) which allows humans to distinguish between hundreds of different foods and beverages. The importance of the sense of smell becomes evident once it is blocked. This may e.g. happen during a severe cold including nasal congestion. In this case, every food appears to be insipid and boring and the joy during consumption is clearly reduced.

For the identification of the crucial odour-active compounds, a concept was developed at the German Research Center for Food Chemistry that combines state-of-the-art analytical separation and structure elucidation techniques with sensory evaluation methodologies. Under the name "Molecular Sensory Science" it has become a major discipline of food related research efforts.

A key technique in the elucidation of the crusial odour-active substances in foods and beverages is gas chromatography-olfactometry. The volatiles isolated from a food or beverage are separated by gas chromatography and in parallel to the detection by an FID or a mass spectrometer, the effluent is evaluated by a trained sniffer. This approach allows to localize odour-active compounds among the bulk of odourless volatiles in the chromatogram. Structure elucidation can then be focused on the odour-active volatiles. In the next step, their exact quantitation allows to estimate their odour potency by comparing the concentrations in the food with the odour threshold value of the respective compound. Reconstitution of the aroma on the basis of the natural concentration data is finally the proof of success. The number of compounds being causally responsible for the overall aroma of a food or beverage is surprisingly small. In most cases, 10-20 key odorants are sufficient to mimick the aroma.

Once these key aroma compounds have been identified, they may serve as valuable tool to optimize the sensory properties of foods and beverages. Today, a major aim is to conserve the odour-active compounds naturally present in the raw materials, e.g. fruits, by application of innovative and gentle processing techniques. In other foods, the quality determining odour-active compounds are not present in the raw materials, but generated during processing. The aroma of chocolate for example developes from a complex interaction of biochemical reaction during cocoa fermentation and thermal reactions during roasting of the fermented beans.

(MSt 2017-08-20)

Current papers of the group.